Change md(4) to use weak symbols as start, end and size for the embedded

root disk. The embedded image is linked into the kernel in the .mfs
section.

Add rules and variables to kern.pre.mk and kern.post.mk that handle the
linking of the image. First objcopy is used to generate an object file.
Then, the object file is linked into the kernel.

Submitted by:	Steve Kiernan <stevek@juniper.net>
Reviewed by:	brooks@
Obtained from: Juniper Networks, Inc.
Differential Revision:	https://reviews.freebsd.org/D2903

3 files changed, 51 insertions, 8 deletions

diff --git a/sys/conf/Makefile.arm b/sys/conf/Makefile.arm
index 86b11c6..af5f7da 100644
--- a/sys/conf/Makefile.arm
+++ b/sys/conf/Makefile.arm
@@ -66,10 +66,6 @@ SYSTEM_LD_TAIL +=;sed s/" + SIZEOF_HEADERS"// ldscript.$M\
 		${KERNEL_KO}.bin; \
 		rm ${FULLKERNEL}.noheader
 
-.if defined(MFS_IMAGE)
-SYSTEM_LD_TAIL += ;sh ${S}/tools/embed_mfs.sh ${KERNEL_KO}.bin ${MFS_IMAGE};
-.endif
-
 FILES_CPU_FUNC = \
 	$S/$M/$M/cpufunc_asm_arm9.S \
 	$S/$M/$M/cpufunc_asm_arm10.S \
diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
index 28ea453..0304120 100644
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -121,7 +121,7 @@ gdbinit:
 .endif
 .endif
 
-${FULLKERNEL}: ${SYSTEM_DEP} vers.o ${MFS_IMAGE}
+${FULLKERNEL}: ${SYSTEM_DEP} vers.o
 	@rm -f ${.TARGET}
 	@echo linking ${.TARGET}
 	${SYSTEM_LD}
@@ -133,9 +133,6 @@ ${FULLKERNEL}: ${SYSTEM_DEP} vers.o ${MFS_IMAGE}
 	${OBJCOPY} --strip-debug ${.TARGET}
 .endif
 	${SYSTEM_LD_TAIL}
-.if defined(MFS_IMAGE)
-	sh ${S}/tools/embed_mfs.sh ${FULLKERNEL} ${MFS_IMAGE}
-.endif
 
 .if !exists(${.OBJDIR}/.depend)
 ${SYSTEM_OBJS}: assym.s vnode_if.h ${BEFORE_DEPEND:M*.h} ${MFILES:T:S/.m$/.h/}
@@ -301,6 +298,27 @@ vnode_if_newproto.h:
 vnode_if_typedef.h:
 	${AWK} -f $S/tools/vnode_if.awk $S/kern/vnode_if.src -q
 
+.if ${MFS_IMAGE:Uno} != "no"
+# Generate an object file from the file system image to embed in the kernel
+# via linking. Make sure the contents are in the mfs section and rename the
+# start/end/size variables to __start_mfs, __stop_mfs, and mfs_size,
+# respectively.
+embedfs_${MFS_IMAGE:T:R}.o: ${MFS_IMAGE}
+	${OBJCOPY} --input-target binary \
+	    --output-target ${EMBEDFS_FORMAT.${MACHINE_ARCH}} \
+	    --binary-architecture ${EMBEDFS_ARCH.${MACHINE_ARCH}} \
+	    ${MFS_IMAGE} ${.TARGET}
+	${OBJCOPY} \
+	    --rename-section .data=mfs,contents,alloc,load,readonly,data \
+	    --redefine-sym \
+		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_size=__mfs_root_size \
+	    --redefine-sym \
+		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_start=mfs_root \
+	    --redefine-sym \
+		_binary_${MFS_IMAGE:C,[^[:alnum:]],_,g}_end=mfs_root_end \
+	    ${.TARGET}
+.endif
+
 # XXX strictly, everything depends on Makefile because changes to ${PROF}
 # only appear there, but we don't handle that.
 
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index cf1b127..3783881 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -191,6 +191,9 @@ SYSTEM_DEP= Makefile ${SYSTEM_OBJS}
 SYSTEM_OBJS= locore.o ${MDOBJS} ${OBJS}
 SYSTEM_OBJS+= ${SYSTEM_CFILES:.c=.o}
 SYSTEM_OBJS+= hack.So
+.if ${MFS_IMAGE:Uno} != "no"
+SYSTEM_OBJS+= embedfs_${MFS_IMAGE:T:R}.o
+.endif
 SYSTEM_LD= @${LD} -Bdynamic -T ${LDSCRIPT} ${_LDFLAGS} --no-warn-mismatch \
 	--warn-common --export-dynamic --dynamic-linker /red/herring \
 	-o ${.TARGET} -X ${SYSTEM_OBJS} vers.o
@@ -222,6 +225,32 @@ MKMODULESENV+=	DEBUG_FLAGS="${DEBUG}"
 .endif
 MKMODULESENV+=	_MPATH="${_MPATH}"
 
+# Architecture and output format arguments for objdump to convert image to
+# object file
+.if ${MFS_IMAGE:Uno} != "no"
+
+.if !defined(EMBEDFS_FORMAT.${MACHINE_ARCH})
+EMBEDFS_FORMAT.${MACHINE_ARCH}!= awk -F'"' '/OUTPUT_FORMAT/ {print $$2}' ${LDSCRIPT}
+.if empty(EMBEDFS_FORMAT.${MACHINE_ARCH})
+.undef EMBEDFS_FORMAT.${MACHINE_ARCH}
+.endif
+.endif
+
+.if !defined(EMBEDFS_ARCH.${MACHINE_ARCH})
+EMBEDFS_ARCH.${MACHINE_ARCH}!= sed -n '/OUTPUT_ARCH/s/.*(\(.*\)).*/\1/p' ${LDSCRIPT}
+.if empty(EMBEDFS_ARCH.${MACHINE_ARCH})
+.undef EMBEDFS_ARCH.${MACHINE_ARCH}
+.endif
+.endif
+
+EMBEDFS_FORMAT.arm?=		elf32-littlearm
+EMBEDFS_FORMAT.armv6?=		elf32-littlearm
+EMBEDFS_FORMAT.mips?=		elf32-tradbigmips
+EMBEDFS_FORMAT.mipsel?=		elf32-tradlittlemips
+EMBEDFS_FORMAT.mips64?=		elf64-tradbigmips
+EMBEDFS_FORMAT.mips64el?=	elf64-tradlittlemips
+.endif
+
 # Detect kernel config options that force stack frames to be turned on.
 DDB_ENABLED!=	grep DDB opt_ddb.h || true ; echo
 DTR_ENABLED!=	grep KDTRACE_FRAME opt_kdtrace.h || true ; echo